PART I

Tutorial:
Clouds for Professionals -- Version 2

Ever
wondered how some of the Terraholics produce those cool looking,
thick clouds?

I’ve
gathered some of the tricks and compiled them here. When I started
off with Terragen, I found it quite a bit difficult to get there.
So, if you’re a newbie, I’ll save you a significant amount of
time if you read through. In case you’re a professional, you might
catch one or another hint of some things you always wanted to
know. Here we go:

Explaning the settings

I’m
not gonna go through all this again, since many others have done
this before. Look at http://www.terrasource.net/#learning
to get the basics. Anyway, I’m gonna tell you something about
clouds in general and which parameters have what type of effect
in my own words.

The
Darkening Slider

This
slider simply controls the overall brightness of the clouds. If
the entire feeling of the sky should be thick and dark – bad weather
style – push the slider to the right.

The
Cloud Color

Use
this one to strengthen the effect of how sunlight colors the clouds
at sunsets or to better create clouds of thunderstorms. For example,
thunder clouds very often look brownish/yellowish shortly before
it all comes down. Play with this setting each time you want to
have the clouds support the overall “feeling” of the scene. The
standard settings are mostly perfect for high noon good weather
scenes.

The
Density Contrast Slider

Well,
if you keep this setting low, the clouds will get brighter in
terms of having more light pass through them the closer the rays
get to the clouds edges and get darker towards the center of the
cloud. If you want clouds to get more dark, slide it to the right.
Having less contrast greatly helps with making clouds more 3-dimensional
(since you will see more details towards the center of the cloud!).
For many scenes, it’s good to leave the slider between 20-30,
with persistence at about 40-50. But if you want the clouds to
be ‘sharp’, a higher contrast will be better. This is also helpful,
if you need well defined and very visible sunbeams.

The
Density Shift Slider

This
one is easy. This setting simply tells the cloud generation algorithm
to cover more space by the clouds. So, more shift, less blue sky
and vice versa.

Clouds
Persistence

Want
to have clouds dissolve more smoothly? Want to get rid of strange
“sprinkles” in the sky? Solution: Lower the persistence, which
makes the boundaries of the clouds more defined. Otherwise, would
you want to have clouds which kind of “spawn” baby clouds beside
them, slide that piece to the right. Usually, in many real scenes
clouds get transformed by the wind, which sometimes devides small
pieces of the larger clouds. But don’t take this to far, it will
screw up your sky scenery a lot! The clouds might appear pixeled
all over.

Clouds
Cast Shadows

The
name says it all. That’s what they do, usually. For realistic
scenes, you need to have this option checked. But in case your
sky looks great but the landscape looks like a deep black hole
just because the clouds cast large shadows, maybe you should consider
to uncheck it. But more effectively, try to increase the shadow
lightness and perhaps increase the exposure factor more.

Where
Cloud Casting Not Used, Use Uniform Shadow

This
has no effect unless you leave “Clouds Cast Shadows” unchecked.
In case it’s uncecked, the slider kind of defines how much the
terrain brighness decreases when you push it to the left– but
this is for the entire terrain, then.